序列化TList of objects（摘自danieleteti的网站）

Some weeks ago a customer asked to me if it is possibile serialize a TList of objects. “Hey, you should use a TObjectList for this”, I said, but he absolutely needs (I dont know why) of a TList.

This is the (simple) sample code tested with Delphi XE2 Update4. Enjoy.

unit Unit4;

interface

uses

  Winapi.Windows,

  Winapi.Messages,

  System.SysUtils,

  System.Variants,

  System.Classes,

  Vcl.Graphics,

  Vcl.Controls,

  Vcl.Forms,

  Vcl.Dialogs,

  Vcl.StdCtrls;

type

  TForm4 = class(TForm)

    Button1: TButton;

    Memo1: TMemo;

    procedure Button1Click(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

  end;

  TPerson = class

  private

    FName: String;

    procedure SetName(const Value: String);

  published

    property Name: String read FName write SetName;

  end;

var

  Form4: TForm4;

implementation

uses

  Contnrs,

  dbxjson,

  dbxjsonreflect;

{$R *.dfm}

procedure TForm4.Button1Click(Sender: TObject);

var

  list: TList;

  m: TJSONMarshal;

  json: TJSONObject;

  p1: TPerson;

  p2: TPerson;

begin

  p1 := TPerson.Create;

  p2 := TPerson.Create;

  try

    p1.Name := 'Daniele Teti';

    p2.Name := 'Peter Parker';

    list := TList.Create;

    try

      list.Add(p1);

      list.Add(p2);

      m := TJSONMarshal.Create;

      try

        // Register a specific converter for field FList

        m.RegisterConverter(TList, 'FList', function(Data: TObject; Field: String): TListOfObjects

          var

            l: TList;

            j: integer;

          begin

            l := Data as TList;

            SetLength(Result, l.Count);

            for j :=  to l.Count -  do

              Result[j] := TObject(l[j]); // HardCast from pointer

          end);

        json := m.Marshal(list) as TJSONObject;

        try

          Memo1.Lines.Text := json.tostring;

        finally

          json.free;

        end;

      finally

        m.free;

      end;

    finally

      list.free;

    end;

  finally

    p1.free;

    p2.free;

  end;

end;

{ TPerson }

procedure TPerson.SetName(const Value: String);

begin

  FName := Value;

end;

end.

The output is, as expected, the following:

{"type":"System.Classes.TList","id":1,"fields":{"FList":[{"type":"Unit4.TPerson","id":2,"fields":{"FName":"Daniele Teti"}},{"type":"Unit4.TPerson","id":3,"fields":{"FName":"Peter Parker"}}],"FCount":2,"FCapacity":4}}

 

http://www.danieleteti.it/how-to-serialize-a-tlist-of-objects-with-delphi/